The present invention relates to a semiconductor device including a plurality of semiconductor parts mounted on a mounting substrate, and more particularly to a mounting structure for the semiconductor parts.
In order to comply with the requirement with respect to miniaturization of semiconductor devices in recent years, there have been semiconductor devices in which a plurality of semiconductor parts are mounted in an overlapping relationship to each other on a mounting substrate to minimize the mounted area of the semiconductor parts.
A related semiconductor device has a spacer between a mounting substrate and a semiconductor integrated circuit board. Because the mounting substrate and the semiconductor integrated circuit board are electrically connected to each other by means of bonding wires, a distance (i.e. a thickness of the spacer) between the mounting substrate and the semiconductor integrated circuit board can be comparatively freely designed.
In contrast herewith, as BGA (ball grid array) is electrically connected to a mounting substrate by the use of a plurality of solder balls formed in arrangement on the lower surface of a package, the distance between the BGA and the mounting substrate cannot be freely designed. In usual, diameters of solder balls of BGA are 0.4 mm to 0.5 mm, and distances between the BGA and the mounting substrate is 0.3 mm to 0.4 mm when the BGA is mounted on the mounting substrate. In the case of chip parts, on the other hand, the maximum values are 0.55 mm with type 1005 mainly used at present and 0.33 mm with small type 0603. In the most cases, therefore, the distance between the BGA and the mounting substrate is less than the thickness of the chip parts (or semiconductor parts). Consequently, the chip parts could not be disposed between the BGA and the mounting substrate.